Dead dolphins on South Australian beaches reach record numbers

Dolphins are without a doubt one of South Australia’s most beloved marine creatures. It is with great sorrow that many beach-goers and coastal residents around the state have reported dolphin bodies, wrecked on our shores this year and in record numbers. The majority of those identified have been Bottlenosed Dolphins (Tursiops aduncus), with only one Common Dolphin (Delphinus delphis) currently identified from Middleton Beach.

The Dolphin Trauma Group is on the case

The Dolphin Trauma Group at the South Australian Museum has been busy collecting these beach-wrecked dolphins, as have AMWRRO, the Australian Marine Wildlife Research & Rescue Organisation. The Australian newspaper revealed on April 30th that thirty-one beach wrecked dolphins had been reported between March 4th and the date of publication. It was also reported that five of these are believed to have died from morbillavirus. Fungal pneumonia has also been found in at least two dolphins, while at least one has been found with E.coli bacteria around the blowhole. AMWRRO have expressed on their website that the discovery of dolphin morbillavirus (DMV) in our waters for the first time “raises concerns that hundreds more animals may be affected within South Australia in coming months.”

The sheer number of beach-wrecked dolphins alone is setting new records for our State. Cath Kemper told the ABC on April 3rd that “sometimes we might get a spate of 4 or so.” At that time, the death toll was around 17 within a month.

After considering the previously limited available information on these dolphin deaths, we decided to put some questions directly to the team involved in the investigations. Staff from the SA Museum, the South Australian Government’s Department of Environment, Water and Natural Resources (DEWNR) and Adelaide University have all been hard at work on this since the first bodies were reported, but their work has a long way to go and many more test results are anticipated.

The problem is very much alive, with DEWNR informing us on May 1st that three additional dolphin mortalities had been reported at Port Lincoln, Port Broughton and Adelaide metropolitan beaches since April 27th. You can see the locations of all reported beach-wrecked dolphins since March 3rd on our map below.

SA beach-wrecked dolphin locations – March 3 to May 1, 2013

We are now very pleased to share with you below the questions we put to the team of scientists and veterinarians, along with their very detailed and timely answers. If you have any further questions about these dolphin mortalities and the scientific investigation, please leave your questions in the comment area below, and we will do our best to seek further information for you. You may also wish to refer to DEWNR’s Dolphin Deaths Frequently Asked Questions page, which contains additional detailed information (last updated April 30th).

How many of the 31 reported beach-wrecked dolphins have undergone (or will undergo) necropsies?

“As many as possible will undergo necropsies. Two carcasses were buried so are not retrievable. Currently, a mother dolphin is guarding one neonate so that cannot be collected until she lets it go, two are being held in regional freezers while transport arrangements are being made and it is unclear whether two were sighted or actually collected. This will be clarified over the next couple of days.

To date, eighteen necropsies have been performed by the SA Museum, two by the University of Adelaide and the Museum plans to undertake another six within the next ten days. Any additional dolphins which died between 1 March and 1 May 2013 will also be necropsied if we are able to obtain the bodies.”

Is the Dolphin Trauma Group looking for signs of acoustic trauma in beach-wrecked dolphins? For example, middle ear fractures or organ damage from the bends?

“One juvenile Common Dolphin has been found. All the others are Bottlenosed Dolphins which are an inshore species and never venture into the depths of waters in which seismic testing is undertaken. Routinely, after necropsy, the bodies are macerated and detailed examination of the skeletons (including the ear bones) are undertaken. This process has not yet been completed for any of the dolphins that have died since 1 March 2013 as the maceration process takes some time.”

Can you please provide a list of all the specific tests being conducted on the dead dolphins?

“Prior to necropsy, every animal is photographed from standard positions, a set or standardised measurements are taken and the animal is weighed. In addition, the age group of the animal is estimated. The blowhole, eyes, anus and genital slit are swabbed for parasites. Any features or injuries of the exterior and of the blubber/muscle interface are noted, documented and frequently photographed. Skin lesions are examined to determine if they occurred pre or post mortem. Blubber thickness is measured and body condition assessed. The body decomposition score is also recorded. The samples taken depend on the state of decomposition of the animal, any lesions of interest and observations during the necropsy but, in general, samples are taken from a variety of sites for X-ray, routine heavy metal and genetic analysis, histology, virology, bacterial culture and, for the dolphins necropsied in early March, for algal toxins. All tests taken for algal toxins have been negative. Gastrointestinal content has also been collected for dietary analysis.”

How many dolphins have tested negative to morbillivirus?

To date, all of the six dolphins tested have returned positive results for morbillivirus.

Special thanks to Cath Kemper (Dolphin Trauma Group, SA Museum) and Georgia Gowing (DEWNR) for their prompt and detailed responses to our questions. If you have information regarding a dolphin mortality, please contact the Adelaide Dolphin Sanctuary on (08) 8240 0193 or email AdelaideDolphinSanctuary@sa.gov.au. If you have discovered a beached whale or dolphin in South Australia, please call the SA Museum’s whale stranding mobile on 0412 708 012.